Anti-clotting methods and apparatus for indwelling catheter tubes

ABSTRACT

Enabled or activated closure and sealing devices in the form of closure balloons, and related methods, are disclosed, which substantially preclude entry and clotting of blood at the distal end of a lumen of an indwelling catheter tube during times when flow therein is not occurring. The closure and sealing balloon is disabled or deactivated to accommodate flow, without clotting, through the lumen of the catheter tube when flow therein is resumed.

FIELD OF THE INVENTION

[0001] The present invention relates generally to catheter tubes andmore specifically to anti-clotting methods and apparatus for cathetertubes.

BACKGROUND

[0002] Typically, for example only, many dialysis medical patients aretreated for a few hours every two or three days. Dialysis is performedby removing blood from the patient through an effluent or egresscatheter tube, processing the removed blood through an artificial kidneymachine to filter impurities from the blood, and returning the cleansedor processed blood to the patient through an influent, infusion oringress catheter tube. The two catheter tubes may be any of severalconfigurations, including but not limited to two essentially separatecatheter tubes, a dual lumen catheter or any other suitableegress/ingress arrangement.

[0003] It is desirable to limit the number of times a vessel of thepatient is penetrated for placement therein of dialysis catheter tubes.Accordingly, once placed, it is desirable for the distal end of theegress and ingress catheter tubes to be left indwelling for an extendedperiod of time to accommodate spaced, repeated dialysis. Accordingly,the indwelling egress and ingress catheter tubes are inactive typicallyfor much longer intervals than they are active. In addition, cathetertubes for other purposes are sometimes left indwelling for long periodsof time and are frequently idle with no flow therethrough. Thisincludes, but is not limited to, the central venous catheter category.

[0004] During idle times, when flow is not occurring in a givenindwelling catheter tube, blood tends to enter the distal opening of theindwelling catheter tube. This is true even when the lumen of thecatheter tube is full of liquid, other than blood, such as saline orheparin. During these idle times, blood flow through the vessel aroundthe outside of the catheter tube tends to evacuate liquid from the lumenat the distal tip of the idle indwelling catheter tube, which isreplaced by blood. This blood in the distal tip of each catheter tubetends to remain stationary, risking the development of a clot.

[0005] When clotting occurs within the lumen at the distal end of acatheter tube, an expensive clot-busting medication, such as Urokinase,is introduced into the proximal end of the catheter tube. After asuitable waiting period, during which the clot is softened, themedication and softened clot are aspirated from the catheter tubethrough the proximal end thereof. Where sufficient softening does notoccur, the expensive clot-busting medication process may be repeated.Sometimes the clot is discharged into the vessel from the lumen using aliquid under positive pressure, which creates undesired risks for thepatient. If all else fails, the catheter tube with the clot therein isremoved from the patient at the vessel puncture site and a newreplacement catheter tube inserted into the vessel.

[0006] Given the foregoing, provision of reliable and inexpensivemethods and apparatus for avoiding or greatly alleviating clotting inindwelling catheter tubes would solve a long standing medical problem.

BRIEF SUMMARY AND OBJECTS OF THE PRESENT INVENTION

[0007] In brief summary, the present invention overcomes orsubstantially alleviates clotting problems heretofore associated withcertain types of catheter tubes. The present invention utilizes anenabled or activated closure and sealing device and related methods tosubstantially preclude entry and clotting of blood at the distal end ofa lumen of an indwelling catheter tube during times when flow therein isnot occurring. The closure and sealing device is disabled or deactivatedto accommodate flow, without clotting, through the lumen of the cathetertube when flow therein is initiated or resumed. In a presently preferredform, the closure device may comprise an inflatable/deflatable balloon,which, when inflated, closes the lumen of the catheter tube at thedistal end thereof. The invention can be configured to accommodateflushing or purging of the lumen of the indwelling catheter tube eitherbefore or after inflated deployment of the balloon closure. The balloonmechanism may be inserted into the patient as the catheter tube isinserted, with the balloon either inflated or deflated; or separatelyafter the catheter tube is first inserted. The invention applies totrimmable and non-trimmable catheters. The balloon may be a separatecomponent or integrated with the catheter tube. Slit valve mechanismsmay be used to control flow through the lumen of the catheter tube, toprevent or alleviate leakage at the proximal end of the catheter tube,and to control fluid flow to and from the balloon.

[0008] In view of the foregoing, it is a primary object of the presentinvention to overcome or materially alleviate clotting problemsheretofore associated with certain types of catheter tubes.

[0009] Another important object is the provision of anti-clottingmethods and apparatus for indwelling catheter tubes.

[0010] A further paramount object is the utilization of a closure andsealing device and related methods which, when the device is activated,substantially precludes entry and clotting of blood at the distal end ofa lumen of an indwelling catheter tube during times when flow therein isnot occurring and/or when the catheter tube and balloon are collectivelyintroduced into the vessel.

[0011] Another dominant object is the provision of a closure and sealingdevice and related methods, which device can be activated to precludeentry and clotting of blood within a lumen of a catheter tube duringintroduction and/or during times when flow therein is not occurring andcan be deactivated to accommodate flow through the lumen of the cathetertube.

[0012] It is another valuable object of the present invention to providean inflatable/deflatable balloon device for selective closure of a lumenof a catheter tube at the distal end thereof, when inflated.

[0013] An additional significant object is the provision of a trimmableor non-trimmable catheter tube in combination with a balloon closuredevice at the distal end of the catheter tube which accommodates use ofa liquid under pressure to flush or purge the lumen of the indwellingcatheter tube, either before or after inflated deployment of the balloonclosure.

[0014] A further valued object is the provision of novel balloonclosures in combination with the distal ends of catheter tubes wherein aslit valve mechanism is used to control flow through the lumen of anassociated catheter tube, to prevent or alleviate leakage at theproximal end of the catheter tube, and/or to control fluid flow to andfrom the balloon.

[0015] These and other objects and features of the present inventionwill be apparent from the detailed description taken with reference tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIGS. 1 and 2 are elevational views partly in cross section of theprior art dialysis catheter tubes, illustrating blood clots within thelumen of each tube at the distal end thereof;

[0017]FIG. 3 is an elevational view partly in cross section of oneconfiguration of the present invention comprising a balloon end closuresealing the lumen of a catheter tube at the distal end thereof;

[0018]FIG. 4 is an enlarged fragmentary view partly in cross section ofthe balloon closure of FIG. 3 unsealed from the interior wall of thecatheter tube by flushing or purging liquid under pressure;

[0019]FIG. 5 is a view similar to FIG. 4 showing the balloon closureresealed after displacement of purging liquid under pressure isdiscontinued;

[0020]FIGS. 6, 7 and 8 are elevational views partly in cross section ofballoon closure in combination with various catheter tubes;

[0021]FIG. 9 is a plan view illustrating structure by which (1) flushingliquid under pressure is displaced through the lumen of a catheter tubeand (2) fluid is displaced to inflate and deflate a balloon closure atthe distal end of the catheter tube;

[0022]FIG. 10 is an enlarged exploded fragmentary plan view partly incross section of the assembly at the proximal end of the catheter tubeof FIG. 9;

[0023]FIGS. 11 and 12 are enlarged fragmentary cross sections of a sealand clamp arrangement at the proximal end of the catheter tube of FIG. 9through which a stem for inflating a balloon closure passes in sealedand clamped relationships respectively, the stem having distance indiciaby which the balloon closure is accurately located inside the lumen atthe distal end of the catheter tube;

[0024]FIG. 13 is an enlarged cross section of the distal end of acatheter tube equipped with an integrated balloon closure;

[0025]FIG. 14 is an enlarged fragmentary cross section of the distal endof a catheter tube equipped with another form of integrated balloonclosure;

[0026]FIG. 15 is a cross section taken along lines 15-15 of FIG. 14;

[0027]FIG. 16 is a fragmentary diagrammatic illustration of a slit valvemechanism used to control inflation and deflation of a balloon closureat the distal end of a catheter tube; and

[0028]FIG. 17 is a fragmentary diagrammatic illustration of a slit valvemechanism used to control purging of the lumen of a catheter tube.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0029] Reference is now made in detail to the drawings wherein likenumerals are used to designate like parts throughout. In reference toFIGS. 1 and 2, which relate to a problem associated with the prior art.Specifically, catheters of various kinds, including but not limited tocentral venous catheters and dialysis catheters are idle for substantialintervals of time. That is to say, flow of liquid through catheter tubesof the type mentioned, is discontinued for extended periods of time andthereafter resumed. In the case of dialysis, blood is removed from thepatient through an effluent or egress catheter lumen 20 and is processedthrough an artificial kidney machine to filter impurities from theblood. The processed blood is then returned to the vessel through aningress catheter lumen 24. See FIGS. 1 and 2. In FIG. 1, the egress andingress lumens 20 and 24 comprise part of the dual lumen catheter,generally designated 26, the dual lumen catheter 26 passing through avenepuncture site 28, which penetrates through the skin 30, tissue 32and vessel wall 22 as such that the distal ends 34 and 36 of the duallumen catheter tube comprising lumens 20 and 24 are indwelling, whiletwo proximal fittings or hubs 38 are outdwelling and are illustrated asbeing closed, in each case, by a removable stopper or plug 40.

[0030] In FIG. 2, side by side catheter tubes 42 and 44 pass through acommon venepuncture site 28′, defining, respectively, lumens 20 and 24.Catheter tubes 42 and 44 comprise distal ends 34 and 36, respectively.The exposed proximal ends 46 and 48 of the catheter tubes 42 and 44 arerespectively equipped with hubs 50 and 52, each of which is illustratedas being closed by a stopper or plug 40. While not shown, sometimes asingle lumen catheter is also left indwelling for substantial intervalswhen flow is not occurring through the lumen thereof. Because it isdesirable to limit the number of times a vessel of a patient ispunctured or penetrated for placement therein of one or more desiredcatheter tubes, catheter tubes which are used only intermittently areretained indwelling so long as there is sufficient medical reason not toremove the same and replace them with other catheters.

[0031] During the interval of time when a catheter or a plurality ofcatheters are left indwelling in a vessel, with no flow occurringthrough the catheter or catheters, blood tends to enter the distal endof each catheter tube, i.e., in the case of FIGS. 1 and 2 at the distalportions of lumens 20 and 24. This is true even when the lumen or lumensare fill of liquid, other than blood, such as saline or heparin. Duringthese idle times, blood flow through the vessel around the outside ofthe catheter tube or tubes tends to evacuate liquid from the lumen orlumens at the distal tip or tips and to replace such evacuated liquid byblood. Because such blood at the distal tip of a catheter lumen tends toremain stationary, clots within the lumen or lumens can and sometimes dodevelop. These clots are identified by the numeral 54 in FIGS. 1 and 2.

[0032] When clotting occurs within a lumen at the distal end of acatheter tube, an expensive clot-busting medication, such as Urokinase,is sometimes introduced into the proximal end of the catheter tube.After a suitable waiting period, during which the clot is softened, themedication and softened clot are aspirated from the catheter tubethrough the proximal end thereof. When sufficient softening does notoccur, the expensive clot-busting medication process may be repeated.Sometimes the clot is discharged into the vessel from the lumen using aliquid under positive pressure, which creates undesired risks for thepatient. If all else fails, the catheter tube with the clot therein isremoved from the patient at the vessel puncture site and a newreplacement catheter is inserted into the vessel.

[0033] Given the foregoing, it should be clear that avoidance of a clotat the distal end of an indwelling catheter tube would be a far bettersolution than trying to deal with a clot once it has developed. Thepresent invention overcomes or substantially alleviates clottingproblems heretofore associated with certain types of catheter tubes. Oneembodiment of the present invention is illustrated in FIG. 3 and isgenerally designated as 60. The catheter assembly 60 comprises acatheter tube 62, having a hollow cylindrical wall 64 defining a lumen66 therein. The distal end 67 of the catheter tube 62 is indwellingwithin vessel 22. The outdwelling portion of the catheter tube 62comprises a Y-adapter 68. One branch 69 of the adapter is connected to asource 70 of saline which is or can be placed under pressure. TheY-adapter 69 can be part of the catheter, but in certain applicationscan preferably be part of the balloon closure assembly as explainedhereinafter in greater detail.

[0034] The main, straight proximal end 71 of the Y-adapter at 68connects to a proximal fitting or hub 72, which comprises an internalseal through which a hollow stem 74 passes. Stem 74 is in fluidcommunication with an internal balloon 76 and an external indicatorballoon 79. The stem 74 connects across a hollow fitting 77 whichcomprises a Luer fitting into which a syringe, generally designated 80,is inserted. Syringe 80 comprises a barrel 82 and a plunger 84. Theamount of saline in the barrel 82 of the syringe is that required tofully inflate the balloon 76. For example, saline may be initiallyloaded into the barrel 82 of the syringe 80 and, upon placement of theballoon 76, in deflated condition, at the distal end 67 of the cathetertube 62, the plunger 84 is advanced to discharge saline under pressurefrom the barrel 82 across the Luer fitting 78, across hollow fitting 77,along hollow stem 74 to inflate the balloon 76 into the configurationillustrated in FIG. 3. The Luer fitting 78, as is conventional,comprises a seal which prevents leakage both when free of the syringe 80and when connected to the syringe. Likewise, the saline from source 70inflates the indicator balloon 79. When balloon 79 is fully inflated,the medical technician or other user knows the internal balloon 76 isfully inflated. Furthermore, the indicator balloon 79 is constructed sothat it will rupture due to excessive pressure before the balloon 76ruptures, to insure safety in use. Also, after placement and beforeinflation of the balloon 76, saline or other appropriate liquid may bedisplaced under pressure through port 69 to purge passageway 66 of anyundesired substances, such as blood or other infusant that may have beenused.

[0035] The balloon 76 and the catheter tube 62 are preserved in therelationship illustrated in FIG. 3 until such time as it is desired toresume flow through the catheter tube 62, in which case the balloon 76is deflated by aspirating saline from balloon 76 into the barrel 82. Theballoon 76, in a deflated condition, may be left near the distal end 67of the catheter tube 62 and infusion of a suitable fluid through thecatheter is accomplished by connection of the fluid source to the arm69. In the alternative, the balloon 76 may be withdrawn from thecatheter tube, which would entail removal of the stop 72, the deflatedballoon 76, the balloon stem 74, the fitting 77, the Luer fitting 78 andthe syringe 80 and, thereafter, connection of the proximal end of themain bore of the catheter tube to other apparatus which accommodatesliquid flow through the lumen 66, in or out as appropriate.

[0036] With the balloon 76 inflated, as illustrated in FIG. 3, blood isnot permitted to back-flow into the lumen 66 and, therefore, clottingwithin the distal end of lumen 66 is avoided. Nevertheless, at one ormore appropriate times, saline from source 70 may be delivered underpressure to the lumen 66 to purge the lumen, which will temporarilydislodge and unseal the balloon 76 from the catheter tube 62,essentially as shown in FIG. 4. Once the delivery of saline underpressure from source 70 is discontinued, the balloon 76 will resume itsclosed, sealed and anti-clotting position, as illustrated in FIG. 5.

[0037] When the anti-clotting embodiment shown and described inconnection with FIG. 3 is used on a dual lumen catheter assembly, of thetype illustrated in FIG. 1, two balloon mechanisms are used of the typedescribed in connection with FIG. 3, one for each lumen 20 and 24. Thisanti-clotting arrangement is illustrated in FIG. 7, which is numeratedconsistent with the numerals used in FIGS. 1 and 3, so far asapplicable.

[0038] Similarly, when two catheters are used, of the type shown in FIG.2, the anti-clotting embodiment of FIG. 3 may be combined therewith inthe manner illustrated in FIG. 8, which has been enumerated so as toconform to the enumeration of FIGS. 2 and 3, so far as applicable.

[0039] In reference to FIG. 6, it is understood by those skilled in theart that some catheters, including catheter tube 80, comprise not only adistal end opening 82, but one or more side ports 84. To prevent entryof blood through one or more ports 84 during times when the cathetertube 80 is not being actively used, an elongated balloon 76′ is providedso that, when inflated, the balloon 76′ not only closes and seals thecatheter tube lumen 86 adjacent the distal end 88 of the catheter tube80, but also closes each side port 84 to prevent entry of bloodtherethrough.

[0040] It is to be understood that the present invention applies totrimmable catheters including but not limited to peripherally insertedcentral catheters (PICC) and to tunnel catheters. These catheters arecharacterized as being trimmable because the length thereof is customsized to the anatomy of a specific patient to equal the distance betweenthe entry site and the desired location of the distal end of thecatheter tube. Typically, this desired length or distance is measuredwith a ruler along but outside the patient. The measured distance istransferred to the catheter tube and the catheter tube is cut (trimmed)to the desired length.

[0041] After the catheter tube is so trimmed, the present invention maybe implemented by inserting balloon closure (obturator) and stem intothe catheter tube while outside the body. The distal end of the balloonclosure is placed adjacent to the distal end of the catheter tube andlocked in this position. Then the catheter tube and balloon with stemmay be simultaneously inserted into a vessel of the patient until thedistal end of the catheter tube is correctly positioned in the patient.

[0042] In the alternative, the locked stem, with proximal hub andballoon may be removed from the catheter tube while it is external ofthe patient and the catheter tube by itself inserted through a puncturesite into the vessel and advanced until the distal end thereof iscorrectly positioned in the patient. Thereafter the balloon and stem maybe inserted into the indwelling catheter tube until the hub associatedwith the stem is seated as sealed within the hub or proximal fitting ofthe catheter tube, which will correctly position the balloon adjacent tothe distal end of the catheter tube.

[0043] Blood leakage through the proximal fitting of the catheter may beprevented by use of a slit valve within the proximal fitting, orminimized by manually collapsing the proximal portion of the cathetertube or placement of the user's thumb over the proximal end, so far aspossible.

[0044] The present invention also applies to non-trimmable cathetertubes as exemplarily explained herein.

[0045] From the foregoing, it is clear that the present inventionutilizes an enabled or activated closure and sealing device, andpractices related methods, to substantially preclude entry and clottingof blood at the distal end of a lumen of an indwelling catheter tubeduring times when flow through the catheter tube is not occurring. Theclosure and sealing device is disabled or deactivated to accommodateresumption of flow, without clotting, through the lumen of the cathetertube. The closure device may comprise an inflatable/deflatable balloonwhich, when inflated, closes the lumen of the catheter tube at thedistal end thereof. The invention may be configured to accommodateflushing of the lumen of the catheter tube either before or afterinflated deployment of the balloon closure.

[0046] With reference to FIGS. 9 through 12, a Touhy-Borst fitting maybe used in conjunction with the present invention to deliver and removesaline under pressure to and from the balloon closure 76 and to deliversaline or other liquid under pressure through the associated cathetertube to purge the interior thereof. More specifically, in reference toFIG. 9, the outdwelling trailing end of a catheter tube 100 isillustrated, where the distal end of the catheter tube 100 is indwellingwithin a vessel of a patient. Within the catheter tube 100 is disposedthe balloon inflating stem 74 described above. The catheter tube 100merges with a female proximal fitting or hub 102, which is connected inliquid-communicating relation with a proximal fitting 104, the interiorof which comprises a hollow passageway. Fitting 104 comprises a distalmale portion 106, which is press-fit into the hub 102 and a proximalhollow tube 108. The distal end of the tube 108 terminates in threads110. See FIG. 10.

[0047] Threads 110 are threaded into a distal female threaded receptacle112 of a hollow Tee piece, generally designated 114. The Tee piece 114comprises a proximal portion 116, which is hollow, and a side port 118and a hub 119, both of which are also hollow. Liquid flow under pressureto purge the lumen of the catheter 100 is introduced via side port 118and passes through the hollow fitting 112, the hollow of tube 108, thehollow of fitting 104, the hollow of tube 106 and the hollow of the hub102 to the lumen of the catheter tube 100. This may be done, forexample, by placing the distal tip of a syringe, generally designated120, into liquid-communicating relation with the hub or sealing Luerfitting 119 of port 118 with the barrel 122 of the syringe 120, when thebarrel 122 is full of a suitable solution, such as saline, and advancingthe plunger 124 to extrude or discharge the saline from the barrel 122under pressure along the path mentioned above. The Luer fittings 78 and119 may comprise a commercially available Halkey-Roberts or equivalentvalve which opens upon reception of the distal end of the syringe 80 or120 and which closes automatically when the syringe is removed. Suchvalves are commonly used on endotracheal tubes and Foley catheters.

[0048] Within the hollow interior 126 of the exteriorly threadedproximal connector 116 is disposed an annular seal 128 of siliconerubber or the like, which comprises a central bore or aperture 130, adistal face 132, a proximal face 134 and an annular edge face 136. Ascan be seen best in FIGS. 11 and 12, the annular or disc-shaped seal 128is snugly positioned within the hollow 126, with the distal face 132continuously abutting shoulders 138 and 140.

[0049] As viewed in FIG. 11, the balloon stem 74 passes snugly butmoveably through the aperture or bore 130 in the seal 128. The stem 74is illustrated as having distance indicia 142 disposed thereon foraccurate placement of the balloon at the distal end of the stem 74directly adjacent the distal end of the catheter tube 100 while thedistal end is indwelling. While distance indicia 142 is referenced tothe distal internal balloon 76 and may extend from the distal balloon 76to the proximal region of the stem 74, in most if not all applicationsmarks 142 are needed only for an appropriate length along a proximalportion of the stem 74 sufficient to allow proper placement of theballoon 76 at the distal end of both trimmable and non-trimmablecatheter tubes as determined by those skilled in the art.

[0050] However, when a double wall cap 144 is threaded upon proximalconnector 116, an internal annular portion 146 compresses the annularseal 128 at surface 134. The overall effect of the compression caused bythe internal annular portion 146 causes the seal 128 to attempt toexpand radially outwardly and radially inwardly. This places sufficientpressure from the seal 128 upon the exterior surface of the stem 74passing through the seal 128 so that the stem 74 can no longer be movedin either a forward or reverse direction in respect to the seal 128. Inother words, the seal 128, responsive to the compaction caused byportion 146, clamps against the stem 74 causing it to be held in adesired position. In this way, the balloon at the distal end of the stem74 is retained in its selected position directly adjacent the distal tipof the catheter tube 100 to function as an anti-clotting closure devicewhich prohibits blood from entering into the distal end of the cathetertube lumen. See FIG. 12.

[0051] In further reference to FIG. 9, there is illustrated a secondsyringe, generally designated 150, which comprises a barrel 152initially loaded with a liquid, such as saline. The syringe 150 alsocomprises a plunger 154. When the plunger 154 is advanced, the liquidwithin the barrel 152 is discharged under pressure into and along thehollow stem 74 to inflate the closure balloon at the distal end of thecatheter tube 100 to close and seal the distal end of the catheter tube.Thus, the balloon is inflated. When the plunger 154 is thereafterretracted, the liquid in the balloon is aspirated along the hollow stem74 into the barrel 150, thereby deflating the balloon.

[0052] Reference is now made to FIG. 13, which illustrates a cathetertube 160 equipped with an integral balloon closure device, generallydesignated 162, for closing and sealing the distal end of the cathetertube 160 to prevent entry of blood during periods when flow is notoccurring within the lumen 164 of the catheter tube, thereby preventingclotting of the blood within the lumen 164. The catheter tube 160comprises a wall 166 which is illustrated as having a uniform thicknessthroughout and uniform inside and outside diameters as well. Within thewall 160 is defined a passageway 168 through which a suitable fluid,such as saline liquid, is displaced from and to a source 170. Source 170may be a syringe of satisfactory capacity.

[0053] The source 170 communicates through a fitting 172 to thepassageway 168 to inflate the balloon 162 and from the interior of theballoon through the passageway 168 and the fitting 172 to the source 170to deflate the balloon 162. The balloon 162 comprises a rounded bladder174, the edges 176 of which are secured to and sealed against shoulders178, using a suitable bonding agent or the like. Shoulders 178 form twoof the three walls of an annular groove 180 into which fluid underpressure is delivered to inflate the bladder 174, displacing the bladder174 from the solid line position to the dotted line position shown inFIG. 13. When it is desired to deflate the bladder 174, the source 170applies a negative or aspirating pressure to the fluid, evacuating thefluid from the groove 180 and passageway 168 to the source 170. Thus,the embodiment illustrated in FIG. 13 provides an integrated cathetertube and distal end closure device version of the present invention.

[0054] Reference is now made to FIGS. 14 and 15, which illustrate afurther catheter with integral balloon embodiment of the presentinvention, generally designated 202. Catheter 202 comprises a cathetertube 203 comprising a one piece wall 204. The wall 204 is bifurcated atlocations 206 (FIG. 15) to define a large central lumen 208, throughwhich blood or other liquid is intended to flow, and a small eccentriclumen 210, through which saline, air or other fluid under pressure isdisplaced to inflate and deflate a closure balloon, as more fullyexplained hereinafter. The distal end of the lumen 210 is closed by aplug 211 or other suitable structure.

[0055] A relatively thin membrane 212 spans internally between thebifurcation points 206. A distal portion 214 of the membrane 212 ispreferably weakened or of reduced strength so that fluid under pressureexpands the weakened portion 214 of the membrane 212 from the solid tothe dotted position, as shown in FIGS. 14 and 15. When the fluidpressure is removed, the memory of the portion 214 causes it to resumeits solid line position, accommodating liquid flow through the centrallumen 208.

[0056] Weakening of the portion 214 may be in any known way, such aschemical treatment, reduced thickness or the like.

[0057] By having a beveled distal edge 216, the catheter tube 204provides very little space for blood to be introduced at the distal endof the catheter tube 204, when the weakened balloon portion 214 isinflated into the dotted line position. See FIG. 14.

[0058] The foregoing description of apparatus and methods emphasizesprevention of refluxing of blood into a catheter tube, when not in use,and prevention of diffusion of blood along with the contents within thecatheter, also when not in use. Some important aspects of this inventionare summarized below.

[0059] Basically, a flexible tube or balloon stem with a Luer fitting onthe proximal end and a balloon on the distal end which is normally inthe shape of an inflated balloon is used. The balloon may be deflated byattaching a syringe to the luer fitting and aspirating the air or otherfluid out of the balloon. The balloon may be so collapsed sufficientlyto advance the balloon and tube or stem into the catheter tube until theballoon is at the distal end of the catheter tube. The syringe caneither be disconnected and allow the balloon to resume its normal shape(conforming to the shape of the central lumen of the catheter tube intowhich it has been placed) or the syringe can be activated to reintroducethe air or other fluid which had been previously removed. Upon removalof the syringe, any excess air or fluid which had been instilled in thesystem would be dispelled from the balloon catheter through the luerfitting, at which time a cap may be placed on the luer fitting.

[0060] In respect to one method of placing a balloon at the distal tipof catheter tube, the balloon is advanced during placement until it isknown that the balloon is slightly beyond tip of catheter tube, eitherby knowing the exact length of catheter tube and observing themeasurement marks inscribed on the stem or it will be advanced untilupon release of negative pressure in the stem, which collapses theballoon, it is noted that there is no resistance to movement of theballoon and stem. Without a syringe or cap on the proximal end of thestem, the stem will be moved outward (retrograde) until resistance isfelt and with another one-half centimeter or so outward movement theballoon will be in the correct position in the catheter tube.

[0061] It is often desirable to use a locking mechanism such as a TouhyBorst adapter to insure that the stem does not move once it is in thedesired position.

[0062] Reference is now made to FIG. 16, which illustrates a furtherembodiment of the present invention by which saline or other suitablefluid under pressure is discharged from and received at source 190,which may be a syringe. The saline or the like flows bi-directionallythrough the stem 74 to and from a balloon closure at the indwellingdistal end of a catheter tube to prevent entry of blood into the tubeand subsequent clotting thereof. Flow to the balloon inflates theballoon, while flow from the balloon to the source 190 deflates theballoon. FIG. 16 illustrates that a two-way slit valve mechanism 192 ispositioned along the length of the tube 74. The two-way slit valvemechanism comprises a slit valve which is normally closed. Thus, acertain pressure differential to cross the slit valve is necessary inorder to cause inflating or deflating fluid flow across the mechanism192. Such slit valve mechanisms are known in the medical field. See, forexample, U.S. Pat. Nos. 5,169,393, 5,201,722, and 5,205,834.

[0063] Likewise, in reference to FIG. 17, a catheter tube 194 maycomprise a side port 196 equipped with a slit valve mechanism 198similar or identical to the slit valve mechanism 192 mentioned above.Thus, saline or like liquid under pressure may be delivered from source200 to the slit valve mechanism 198. When a suitable pressuredifferential threshold is reached, the slit valve within the mechanism198 opens and the liquid under pressure proceeds into the lumen 195 ofthe catheter tube 194 to purge the interior of the catheter tube 194,either before or after inflating of a balloon closure at the distal endof the catheter tube for the purpose of preventing clotting of blood atthe distal end of the catheter tube.

[0064] The invention may be embodied in other specific forms withoutdeparting from the spirit of the central characteristics thereof. Thepresent embodiments therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:
 1. Amethod of addressing the problem of clotting in an idle catheter tubeindwelling within a vessel of a medical patient comprising the acts of:advancing a deflated balloon along a hollow interior of the idleindwelling catheter tube to a distal end thereof; inflating the balloonto close and seal the hollow interior at the distal end of the idleindwelling catheter tube to deny blood access to the hollow interior. 2.A method according to claim 1 further comprising the act of purging thehollow interior of the catheter tube in a proximal-to-distal directionwith a suitable liquid under pressure.
 3. A method according to claim 2wherein the purging act precedes the inflating act.
 4. A methodaccording to claim 2 wherein the purging act follows the inflating act,the pressure of the liquid temporarily unsealing the inflated balloon.5. A method according to claim 2 wherein the purging act takes placeacross a slit valve.
 6. A method according to claim 1 further comprisingthe acts of deflating the balloon and causing flow through the hollowinterior of the catheter tube.
 7. A method according to claim 6 furthercomprising the act of withdrawing the balloon after the deflating actand before the causing act.
 8. A method according to claim 6 wherein thedeflating act takes place across a slit valve.
 9. A method according toclaim 1 wherein the inflating act takes place across a slit valve.
 10. Amethod of addressing the problem of clotting in idle ingress and egresscompanion catheter tubes indwelling within a vessel of a medicalpatient, comprising the acts of: advancing a deflated balloon along ahollow interior of each idle ingress and egress catheter tube to adistal end of each; inflating the respective balloons to close and sealthe hollow interior at the distal end of each catheter tube, therebydenying blood access to the hollow interior of each.
 11. A methodaccording to claim 10 further comprising the act of purging the hollowinterior of one or both catheter tubes in a proximal-to-distal directionwith a suitable liquid under pressure.
 12. A method according to claim11 wherein the purging act precedes the inflating act.
 13. A methodaccording to claim 11 wherein the purging act follows the inflating act,the pressure of the liquid temporarily unsealing the inflated balloon.14. A method according to claim 11 wherein the purging act takes placeacross a slit valve.
 15. A method according to claim 10 furthercomprising the acts of deflating both balloons and causing ingress andegress flow through the respective hollow interiors of the cathetertubes.
 16. A method according to claim 15 further comprising the act ofwithdrawing the balloon after the deflating act and before the causingact.
 17. A method according to claim 15 wherein the deflating act takesplace across a slit valve.
 18. A method according to claim 10 whereinthe inflating act takes place across a slit valve.
 19. A method ofaddressing the problem of clotting in a catheter tube indwelling withina vessel of a patient comprising the acts of: terminating flow along ahollow interior passageway of the indwelling catheter tube; after theterminating act, inflating a balloon to close and seal the hollowinterior passageway at a distal end of the indwelling catheter tube todeny blood in the vessel access to the hollow interior.
 20. A methodaccording to claim 19 further comprising the act of purging the hollowinterior of the catheter tube in a proximal-to-distal direction with asuitable liquid under pressure.
 21. A method according to claim 20wherein the purging act precedes the inflating act.
 22. A methodaccording to claim 20 wherein the purging act follows the inflating act,the pressure of the liquid temporarily unsealing the inflated balloon.23. A method according to claim 20 wherein the purging act takes placeacross a slit valve.
 24. A method according to claim 19 furthercomprising the acts of deflating the balloon and causing flow throughthe hollow interior passageway of the catheter tube.
 25. A methodaccording to claim 19 further comprising the act of withdrawing theballoon after the deflating act and before the causing act.
 26. A methodaccording to claim 24 wherein the deflating act takes place across aslit valve.
 27. A method according to claim 19 wherein the inflating acttakes place across a slit valve.
 28. A method of addressing the problemof clotting in ingress and egress companion catheter tubes indwellingwithin a vessel of a medical patient, comprising the acts of:terminating ingress and egress flow along hollow interior passageways ofthe indwelling catheter tubes, respectively; after the terminating step,inflating balloons to close and seal the respective hollow interiorpassageways at the distal ends of the indwelling ingress and egresscatheter tubes to deny blood in the vessel access to the hollow interiorpassageways.
 29. A method according to claim 28 further comprising theact of purging one or both hollow interior passageways in aproximal-to-distal direction with a suitable liquid under pressure. 30.A method according to claim 29 wherein the purging step precedes theinflating step.
 31. A method according to claim 27 wherein the purgingstep follows the inflating step, the pressure of the liquid temporarilyunsealing the inflated balloon.
 32. A method according to claim 29wherein the purging act takes place across a slit valve.
 33. A methodaccording to claim 28 further comprising the acts of deflating theballoons and causing ingress and egress flow through the hollow interiorpassageways, respectively.
 34. A method according to claim 33 whereinthe deflating act takes place across a slit valve.
 35. A methodaccording to claim 28 wherein the inflating act takes place across aslit valve.
 36. In combination, a catheter tube for selective flowthrough a hollow passageway of the catheter tube to or from a patientand a balloon selectively inflated to close and seal the hollowpassageway at a distal end of the catheter tube against entry of bloodwhen flow is not occurring through the hollow passageway.
 37. Acombination according to claim 36 wherein the balloon is carried near adistal end of an inflation/deflation stem extending within the hollowpassageway for substantially the full length of the catheter tube.
 38. Acombination according to claim 37 wherein the stem carries distanceindicia for locating the balloon at the distal end of the catheter tube.39. A combination according to claim 37 wherein a seal is interposedbetween the catheter tube and the stem within the hollow passageway at aproximal end of the catheter tube, the stem being selectivelydisplaceable along the hollow passageway through a central opening inthe seal.
 40. A combination according to claim 39 wherein the seal isselectively compressed by a control to clamp against the stem to preventstem displacement.
 41. A combination according to claim 36 wherein theballoon is carried by the catheter tube within the hollow passageway atthe distal end of the catheter tube.
 42. A combination according toclaim 36 wherein the balloon comprises a weak portion of a wall of thecatheter tube.
 43. A combination according to claim 41 furthercomprising a pathway along the catheter tube by which fluid underpressure is delivered to and removed from the balloon to selectivelyinflate and deflate the balloon.
 44. A combination according to claim 36further comprising a port adjacent the proximal end of the catheter tubeby which a flushing liquid under pressure is selectively displacedproximal-to-distal within the hollow passageway of the catheter tube.45. In combination, companion ingress and egress catheter tubes forselective flow through a hollow passageway in each catheter tuberespectively to and from the patient and a balloon associated with eachcatheter to accommodating selective inflation of the balloons togenerally concurrently close and seal the two hollow passageways atrespective distal ends of the ingress and egress catheter tubes againstentry of blood from a vessel of the patient when flow is not occurringthrough the hollow passageways.
 46. A combination according to claim 45wherein the balloons are carried near distal ends of spacedinflation/deflation stems extending respectively within the hollowpassageways for substantially the full length of the respective cathetertubes.
 47. A combination according to claim 46 wherein a seal isinterposed between each catheter tube and the associated stem within thehollow passageway of said catheter tube at a proximal end of saidcatheter tube, each stem being selectively displaceable through acentral opening within the associated seal.
 48. A combination accordingto claim 47 wherein each seal is selectively compressed by a control toclamp against the associated stem to prevent stem displacement.
 49. Acombination according to claim 45 wherein each balloon is carried by theassociated catheter tube within the hollow passageway at the distal endthereof.
 50. A combination according to claim 47 further comprising apathway along each catheter tube by which fluid under pressure isdelivered to the associated balloon to selectively inflate and deflatethe associated balloon.
 51. A combination according to claim 45 furthercomprising a port near the proximal end of each catheter tube by which aflushing liquid under pressure is selectively displacedproximal-to-distal within the hollow passageways of the catheter tubes.52. A method of addressing the problem of clotting in an idle cathetertube placed within a vessel of a medical patient comprising the acts of:advancing a deflated balloon along a hollow interior of the idlecatheter tube to a distal end thereof prior to placement of the cathetertube in the vessel; inflating the balloon to close and seal the hollowinterior at the distal end of the catheter tube; collectivelyintroducing the distal end of the catheter tube and the inflated ballooninto the vessel.
 53. A method according to claim 52 further comprisingthe acts of deflating the indwelling balloon and accommodating liquidflow through the catheter tube.
 54. A method of addressing the problemof clotting in idle ingress and egress companion catheter tubes placedwithin a vessel of a medical patient, comprising the acts of: advancinga deflated balloon along a hollow interior of each idle ingress andegress catheter tube to a distal end of each prior to placement ofeither catheter tube in the vessel; inflating the respective balloons toclose and seal the hollow interior at the distal end of each cathetertube; introducing each inflated balloon and the distal end of theassociated catheter tube together into the vessel.